The overall objective of this project is to lessen or eliminate body protein losses which accompany severe trauma, especially in order subjects. For this purpose, the effects of post-trauma dietary changes and supplements are being studied in previously developed animal models. Special attention is being paid to differences in the needs for certain nutrients by young and old animals in the absence and presence of trauma and the effect of those nutrients on certain aspects of the wound healing process. It is planned to investigate the quantitative aspects of the arginine requirement for maximum post-trauma nitrogen retention and optimal wound healing in young and old animals, with special emphasis on skin breaking strength and collagen synthesis. We will then investigate the usefulness of other supplements (amino acids and trace minerals) on nitrogen retention and wound healing, especially in old animals. While we have had some encouraging results with branched-chain amino acids, our first trial with zinc did not yield any new information. Finally, we are planning to expand and confirm the work on the differential amino acid requirements for optimal growth of kidney cells from young and old rats in primary cell culture by testing additional amino acids and, if possible, investigate the mode of action of the previously observed differences in requirements of cells from donors of various ages.